Systems and methods for protecting against relay attacks

ABSTRACT

Systems, methods, and devices are disclosed for preventing relay attacks. A user device may receive (e.g., when proximate to the first access device), from an intervening device, device identification data for a first access device. A message may be received from a second access device via the intervening device. The message may include a digital signature generated based at least in part on second access device identification data. The user device may validate the message utilizing the digital signature and a public key. If the message is invalid, the user device may discard the message. If the message is valid, (e.g., unaltered), the user device may determine that the user has not confirmed an intent to interact with the second access device and may terminate an further interaction with the second access device accordingly.

The present application claims priority to U.S. Provisional ApplicationNo. 62/591,708, filed on Nov. 28, 2017, the disclosure of which isincorporated herein by reference in its entirety for all purposes.

BACKGROUND

Relay attacks are possible in contact and contactless accesstransactions, such as payment transactions between a contactless deviceand a contactless terminal. For example, an attacker (e.g., one or morepeople working together to steal information or defraud legitimateusers) can use two wireless enabled mobile devices, and two mobileapplications on the wireless enabled mobile devices to conduct a relayattack. In a typical relay attack, the attacker uses a first mobiledevice with a first mobile application to tap and communicate with acontactless device in the victim's pocket. The attacker can use a secondmobile device with a second mobile application, to tap and communicatewith a contactless terminal at, for example, a merchant or otherresource provider.

Command messages issued by the contactless terminal are relayed from thesecond mobile device to the first mobile device, and are then receivedby the victim's contactless device. The victim's contactless device thenresponds to the command messages. Access information on the device(e.g., payment information such as a primary account number (PAN)) canthen be relayed from the first mobile device to the second mobiledevice, and then to the contactless terminal. By performing such a relayattack, the attacker can conduct an access transaction (e.g., a purchasetransaction) using the victim's contactless device without takingvictim's device from his/her possession. Although this particularexample is one which involves a merchant, it is understood that thisproblem can exist in other situations where access to a resource isdesired (e.g., an attempt to access a building, or an attempt to accessdata inside of a computer).

Mobile transactions that use Bluetooth Low Energy (BLE) to communicatebetween the contactless device and the contactless terminal typicallyoccur with a close proximity between the device and the terminal.However, these transactions are still susceptible to relay attacks.

The embodiments described herein solve these problems, both individuallyand collectively.

BRIEF SUMMARY

One embodiment of the disclosure is directed to a method. The method maycomprise receiving, by a user device from an intervening device, firstaccess device identification data for a first access device. The methodmay further comprise receiving, by the user device that is proximate tothe first access device, a message from a second access device via theintervening device. In some embodiments, the message may comprisemessage data including at least second access device identification dataand a digital signature that is created by signing a hash of the atleast second access device identification data with a private key of apublic/private key pair associated with the second access device. Themethod may further comprise obtaining the hash from the digitalsignature using a public key. The method may further comprise generatingan additional hash of the message data. The method may further comprisecomparing, by the user device, the hash to the additional hash. Themethod may further comprise determining, by the user device, if the hashmatches the additional hash. The method may further comprise, when thehash does not match the additional hash, automatically terminating, bythe user device, any further interaction with the second access device.The method may further comprise, when the hash matches the additionalhash: determining that a user of the user device has not confirmed anintent to interact with the second access device, and terminating anyfurther interaction with the second access device based at least in parton determining that the user has not confirmed an intent to interactwith the second access device.

Another embodiment of the disclosure is directed to a user device. Insome embodiments, the user device may comprise a processor and anon-transitory computer readable medium. In some embodiments, thecomputer readable medium may comprise code, executable by the processor,for implementing any of the methods described herein.

Another embodiment of the disclosure is directed to a system. The systemmay include at least one user device and at least one access device. Insome embodiments, the user device and/or the access device may comprisea processor and a non-transitory computer readable medium. In someembodiments, the computer readable medium may comprise code, executableby the processor(s), for implementing any of the methods describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary relay attack,according to some embodiments.

FIG. 2 illustrates an exemplary user interface for establishing aconnection to an access device, according to some embodiments.

FIG. 3 illustrates an exemplary user interface for confirming aninteraction with an access device, according to some embodiments.

FIG. 4 shows a block diagram illustrating an exemplary method forpreventing a relay attack, according to some embodiments.

FIG. 5 shows a schematic diagram illustrating an exemplary method forgenerating a digital signature, according to some embodiments.

FIG. 6 shows a block diagram illustrating another exemplary method forpreventing a relay attack, according to some embodiments.

FIG. 7 shows a block diagram illustrating yet another exemplary methodfor preventing a relay attack, according to some embodiments.

FIG. 8 shows a block diagram illustrating yet another exemplary methodfor preventing a relay attack, according to some embodiments.

FIG. 9 shows a block diagram illustrating still one further exemplarymethod for preventing a relay attack, according to some embodiments.

FIG. 10 shows a block diagram of an exemplary user device according toan embodiment of the invention.

FIG. 11 shows a block diagram of an exemplary access device according toan embodiment of the invention.

FIG. 12 shows a block diagram illustrating a transaction processingsystem.

FIG. 13 shows a block diagram illustrating a building access system.

DETAILED DESCRIPTION

Bluetooth Low Energy (BLE) is a communications technology that isavailable in most modern smart phones. BLE technology has been leveragedfor mobile payments. A feature of BLE that potentially makes itattractive for low friction interactions is that establishing aconnection between devices (such as an access device and a user's phone)is easy. For example, when connecting one device to another, there is noneed to exchange a PIN or passphrase, as is the case for traditionalBluetooth.

However, the widespread availability of BLE capabilities in userdevices, together with the simplicity of establishing a BLE connectionbetween user devices and access devices, unfortunately harbors thedesire for fraudsters to develop mobile applications that can mimic aBLE access device. Without protections at the application protocollevel, it is possible for a fraudster to perform a relay attack. Forexample, a fraudster could mimic an access device with which a userdevice is attempting to interact, and could convince the user of theuser device to connect to the fraudulent device instead of the accessdevice. Instead of communicating to the local authentic access device,the fraudster could establish an extended communication channel to anaccomplice at a remote access device, and together the fraudsters'devices could manipulate the communications protocol to cause the userto unintentionally interact with a remote access device rather than theaccess device the user intends.

Prior to discussing specific embodiments of the invention, some termsmay be described in detail.

A “user device” may comprise any suitable electronic device that may betransported and operated by a user, which may also provide remotecommunication capabilities to a network. Examples of remotecommunication capabilities include using a mobile phone (wireless)network, Bluetooth®, Bluetooth Low Energy® (BLE), wireless data network(e.g. 3G, 4G or similar networks), Wi-Fi, Wi-Max, or any othercommunication medium that may provide access to a network such as theInternet or a private network. Examples of user devices include mobilephones (e.g. cellular phones), PDAs, tablet computers, net books, laptopcomputers, personal music players, hand-held specialized readers, etc.Further examples of user devices include wearable devices, such as smartwatches, fitness bands, ankle bracelets, rings, earrings, etc., as wellas automobiles with remote communication capabilities. A user device maycomprise any suitable hardware and software for performing suchfunctions, and may also include multiple devices or components (e.g.when a device has remote access to a network by tethering to anotherdevice—i.e. using the other device as a modem—both devices takentogether may be considered a single user device).

“Interaction data” may include any suitable information associated withan interaction between an access device and a user device. Interactiondata may include any suitable data associated with an interaction (e.g.,a BLE advertisement message, a purchase and/or pre-authorizationtransaction, etc.). In some embodiments, interaction data may includeany suitable combination of: identification data associated with anaccess device (e.g., one or more identifiers of an access device),identification information associated with a user device (e.g., one ormore identifiers associated with a user device), an interaction value(e.g., a transaction amount such as a preauthorization amount and/orpurchase price of a transaction), payment data (e.g., a payment accountidentifier associated with a payment account), one or more locationseach associated with an access device and/or a user device, or anysuitable information. Examples of payment data may include a PAN(primary account number or “account number”), user name, expirationdate, CW (card verification value), dCVV (dynamic card verificationvalue), CW2 (card verification value 2), CVC3 card verification values,etc. CW2 is generally understood to be a static verification valueassociated with a payment device. CW2 values are generally visible to auser (e.g., a consumer), whereas CVV and dCW values are typicallyembedded in memory or authorization request messages and are not readilyknown to the user (although they are known to the issuer and paymentprocessors). Payment data may be any information that identifies or isassociated with a payment account. Payment data may be provided in orderto make a payment from a payment account. Payment data can also includea user name, an expiration date, a gift card number or code, and anyother suitable information.

An “application” may be computer code or other data stored on a computerreadable medium (e.g. memory element or secure element) that may beexecutable by a processor to complete a task.

A “user” may include an individual. In some embodiments, a user may beassociated with one or more personal accounts and/or mobile devices. Theuser may also be referred to as a cardholder, account holder, orconsumer.

A “resource provider” may be an entity that can provide a resource suchas goods, services, information, and/or access. Examples of a resourceprovider includes merchants, access devices, secure data access points,etc. A “merchant” may typically be an entity that engages intransactions and can sell goods or services, or provide access to goodsor services.

An “acquirer” may typically be a business entity (e.g., a commercialbank) that has a business relationship with a particular merchant orother entity. Some entities can perform both issuer and acquirerfunctions. Some embodiments may encompass such single entityissuer-acquirers. An acquirer may operate an acquirer computer, whichcan also be generically referred to as a “transport computer”.

An “authorizing entity” may be an entity that authorizes a request.Examples of an authorizing entity may be an issuer, a governmentalagency, a document repository, an access administrator, etc. An “issuer”may typically refer to a business entity (e.g., a bank) that maintainsan account for a user. An issuer may also issue payment credentialsstored on a user device, such as a cellular telephone, smart card,tablet, or laptop to the consumer.

An “access device” may be any suitable device that provides access to aremote system. An access device may also be used for communicating witha user device, a resource provider computer, a processing networkcomputer, an authorizing entity computer, and/or any other suitablesystem. An access device may generally be located in any suitablelocation, such as at the location of a merchant, or at an accesslocation of a building as another example. An access device may be inany suitable form. Some examples of access devices include POS or pointof sale devices (e.g., POS terminals), cellular phones, PDAs, personalcomputers (PCs), tablet PCs, hand-held specialized readers, set-topboxes, electronic cash registers (ECRs), automated teller machines(ATMs), virtual cash registers (VCRs), kiosks, security systems, accesssystems, and the like. An access device may use any suitable contact orcontactless mode of operation to send or receive data from, orassociated with, a user device. In some embodiments, an access devicemay be configured to communicate with a user device based at least inpart on a short-range communications protocol such as Bluetooth® and/orBLE. In some embodiments, an access device may be further configured toutilize any suitable wired and/or wireless network to communication witha resource provider computer, a processing network computer, anauthorizing entity computer, and/or any other suitable system. In someembodiments, where an access device may comprise a POS terminal, anysuitable POS terminal may be used and may include a reader, a processor,and a computer-readable medium. A reader may include any suitablecontact or contactless mode of operation. For example, exemplary cardreaders can include radio frequency (RF) antennas, optical scanners, barcode readers, or magnetic stripe readers to interact with a paymentdevice and/or mobile device. In some embodiments, a cellular phone,tablet, or other dedicated wireless device used as a POS terminal may bereferred to as a mobile point of sale or an “mPOS” terminal.

An “authorization request message” may be an electronic message thatrequests authorization for a transaction. In some embodiments, it issent to a transaction processing computer and/or an issuer of a paymentcard to request authorization for a transaction. An authorizationrequest message according to some embodiments may comply with ISO 8583,which is a standard for systems that exchange electronic transactioninformation associated with a payment made by a user using a paymentdevice or payment account. The authorization request message may includean issuer account identifier that may be associated with a paymentdevice or payment account. An authorization request message may alsocomprise additional data elements corresponding to “identificationinformation” including, by way of example only: a service code, a CW(card verification value), a dCW (dynamic card verification value), aPAN (primary account number or “account number”), a payment token, auser name, an expiration date, etc. An authorization request message mayalso comprise “transaction information,” such as any informationassociated with a current transaction, such as the transaction amount,merchant identifier, merchant location, acquirer bank identificationnumber (BIN), card acceptor ID, information identifying items beingpurchased, etc., as well as any other information that may be utilizedin determining whether to identify and/or authorize a transaction.

An “authorization response message” may be a message that responds to anauthorization request. In some cases, it may be an electronic messagereply to an authorization request message generated by an issuingfinancial institution or a transaction processing computer. Theauthorization response message may include, by way of example only, oneor more of the following status indicators: Approval—transaction wasapproved; Decline—transaction was not approved; or Call Center—responsepending more information, merchant must call the toll-free authorizationphone number. The authorization response message may also include anauthorization code, which may be a code that a credit card issuing bankreturns in response to an authorization request message in an electronicmessage (either directly or through the transaction processing computer)to the merchant's access device (e.g. POS equipment) that indicatesapproval of the transaction. The code may serve as proof ofauthorization. As noted above, in some embodiments, a transactionprocessing computer may generate or forward the authorization responsemessage to the merchant.

A “server computer” may include a powerful computer or cluster ofcomputers. For example, the server computer can be a large mainframe, aminicomputer cluster, or a group of servers functioning as a unit. Inone example, the server computer may be a database server coupled to aWeb server. The server computer may be coupled to a database and mayinclude any hardware, software, other logic, or combination of thepreceding for servicing the requests from one or more client computers.The server computer may comprise one or more computational apparatusesand may use any of a variety of computing structures, arrangements, andcompilations for servicing the requests from one or more clientcomputers.

FIG. 1 is a block diagram 100 illustrating an exemplary relay attack,according to some embodiments. The example depicted in FIG. 1 shows howfraudsters may compromise an interaction between a user device 102 andan access device 104-1 using a relay attack. FIG. 1 includes a userdevice 102, an access device 104-1, an access device 104-2, anintervening device 106-1, and an intervening device 106-2, although anysuitable number and/or type of devices may be utilized in otherembodiments. As a non-limiting example, the access devices 104-1 and104-2 may each be situated at separate fuel pump devices (and/oroperating as part of a respective fuel pump device) at one or more gasstations.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. The identification data may be in any form. By way ofexample, the identification data may include an identifier of a resourceprovider (e.g., a merchant, such as “SuperGas,” “SuperGas at 4th andBroadway, Seattle, Wash.”, or the like). In some embodiments, theidentification data associated with the access device 104-1 may furtherinclude a device identifier (e.g., “pump 1”). The user device 102 mayapproach the access device 104-1 to breach a threshold distance from theaccess device 104-1 (e.g., within range of receiving short-rangewireless messages of the short-range wireless communications protocolsuch as BLE).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102. In some embodiments, the intervening device 106-1 mayalter the advertisement message (e.g., the identification data) prior torelaying the message to the user device 102, while in other embodiments,the intervening device 106-1 may leave the advertisement messageunaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface of FIG. 2. FIG. 2 illustrates an exemplary userinterface 200 for establishing a connection to a BLE enabled accessdevice, according to some embodiments. As depicted in FIG. 2, userinterface 200 may include text 202. In some embodiments, text 202 mayindicate an intent to connect to a particular access device. As anon-limiting example, the text 202 may include some portion of theidentification data received at step 3 of FIG. 1. As depicted, the text202 may indicate that the user intends to establish a connection withaccess device 1, terminal 1. In the example, provided in FIG. 1, theuser interface 200 may include text 202 that indicates that the userintends to establish a connection with “SuperGas, Pump 1.” The userinterface 200 may include a confirmation button 204 and/or acancellation button 206. Upon selected the confirmation button 204 (orany suitable user interface element configured to be associated with aconfirmation of the intent indicated by text 202), the user device 102be configured to perform further operations. The specific user interfaceelements and/or format of the user interface 200 may vary.

Returning to the FIG. 1, upon presenting the user interface 200 andreceiving indication that the user has confirmed an intent to establisha connection with “SuperGas, Pump 1,” a connection may be establishedutilizing any suitable short-range wireless protocol (e.g., BLE) betweenthe intervening device 106-1 and the user device 102. Thus, based onrelaying the message at step 2, a fraudster may establish a BLEconnection between a first fraudulent contactless device (interveningdevice 106-1) and the user device 102. The user of the user device 102may believe (e.g., based on the text 202 provided in user interface 200of FIG. 2) that they are connecting to the access device 104-1. However,the user device 102 may actually be connected to the fraudster's device(e.g., intervening device 106-1).

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 can connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 4. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas” at “Pump 4”). The interveningdevice 106-2 may connect (or otherwise transmit data) via a second BLEconnection to the access device 104-2 at step 5.

In this fraudulent transaction flow, the intervening device 106-2 mayreceive interaction data (e.g., including identification informationassociated with the access device 104-2, an interaction value such as apre-authorization amount, etc.) from the access device 104-2. Theintervening device 106-2 may relay the received interaction data to theintervening device 106-1 at step 7.

In some attacks, the intervening device 106-1 (and/or the interveningdevice 106-2) may alter the interaction data provided by the accessdevice 104-2. As a non-limiting example, the intervening device 106-1may alter the identification data to indicate that the interaction datawas provided by the access device 104-1 rather than the access device104-2. More specifically, intervening device 106-1 and/or 106-2 mayalter the interaction data associated with “OtherGas, Pump 4” to“SuperGas, Pump 1”. This altered interaction data may be relayed to theuser device 102 at step 9. Reception of this altered interaction datamay cause the user device 102 to present another user interface (e.g.,the user interface 300 of FIG. 3) to confirm an interaction between theuser device 104 and the intervening device 106-1 purporting to be theaccess device 104-1. FIG. 3 illustrates an exemplary user interface 300for confirming an interaction with a BLE enabled access device,according to some embodiments. As a non-limiting example, the userinterface 300 may include text 302 which, as depicted in FIG. 3,indicates that the interaction is to be conducted with “Access Device 1,terminal 1.” In the ongoing example of FIG. 1, the text 302 may indicatethat an interaction is to occur with access device 104-1 (e.g., “Proceedwith pre-authorizing $99 at SuperGas, Pump 1). It should be appreciatedthat the text 302 may include any suitable portion of the interactiondata provided by the access device 104-2 and/or altered by theintervening devices 106-1 and/or 106-2.

In some embodiments, the user interface 300 may be configured to receivebiometric information utilizing any suitable biometric input device ofthe user device 102. By way of example, the user may indicate an intentto perform the interaction (e.g., a pre-authorization) by scanning hisfingerprint via a fingerprint reader at the user device 102. Anysuitable mechanism for indicating an intent to perform the interactionmay be utilized (e.g., via a similar a button similar to theconfirmation button 204 of FIG. 2, via another suitable biometric inputdevice (e.g., a camera, a retina reader, and iris scanner, etc.). Insome embodiments, the user interface 300 may further includecancellation button 304, or a similar interface element, for indicatingthat the user does not intend to perform the interaction indicated intext 302.

Returning to the ongoing example of FIG. 1, since intervening device106-1 has previously presented itself as “SuperGas, Pump 1” to the userdevice 102, the user may be fooled into thinking that his user device102 is interacting with the access device 104-1 (e.g., the “SuperGas”pump located near the user device 102) to perform the transaction, whenin fact it is actually interacting with the access device 104-2 (the“OtherGas” pump) via intervening devices 106-1 and 106-2. As a result,the user may indicate his intent to perform the interaction based onreading the text 302 of FIG. 3 thinking the interaction is withSuperGas, Pump 1, when in fact the user device 102 is not interactingwith access device 104-1 at all.

Upon receiving an indication that the user intends to perform theinteraction, the user device 102 may be configured to provide paymentdata at step 10. For example, an application operating on the userdevice 102 may generate chip data, which is relayed via interveningdevice 106-1 to intervening device 106-2 at step 11. At step 12, theintervening device 106-2 provides the payment data to the access device104-2.

This may enable the fraudsters accomplice (e.g., operating interveningdevice 106-2) to fill their own gas tank, potentially for a much largeramount than the real user intended. In a simple relay attack situation,the real user may not even get a chance to fill their own tank. That is,intervening device 106-1 could simply terminate the BLE connection withthe user device 102 as soon as it has the data necessary to perform thefraudulent transaction.

It can be appreciated that there are many variations to this type ofattack. The above description is only one example. It can also beappreciated that the provider of access device 104-1 (e.g., a merchant“SuperGas”) is not in collusion with the fraudster. As far as theprovider of the access device 104-2 (e.g., a merchant “OtherGas”) isconcerned, the intervening device 106-2 appears to be the device of agenuine user. As a result, the provider of the access device 104-2 isalso unknowingly made a party to the fraudulent transaction.

The relay attack described above is possible because there is no checkthat the access device with which the user believes they are interactingis the same as the access device with which the actual interaction isbeing performed.

FIG. 4 shows a block diagram illustrating an exemplary method 400 forpreventing a relay attack, according to some embodiments. FIG. 4illustrates a use case in which an access device (e.g., access device104-2) digitally signs transmitted data utilizing a private key. Thetransmission may include the corresponding public key such that, if anintervening device modifies the data, the user device 102 may identifythe fact that the data has been modified by validating the digitalsignature using the public key.

In the example depicted in FIG. 4, the user device 102 may be configuredwith encryption data 402. In some embodiments, the encryption data 402may include a certificate issued by a certificate authority (notdepicted). In some embodiments, the certificate can be a Europay,Mastercard® and Visa® (EMV) certificate. In some embodiments, thecertificate may include a public key associated with the user device 102as digitally signed by the certificate authority utilizing a private keyassociated with the certificate authority. The encryption data 402 mayfurther include a private key (e.g., a private key associated with thecertified public key that is digitally signed by the certificateauthority) that is associated with the user device 104. The accessdevices 104-1 and 104-2 may each be configured to generate encryptiondata 404 and 406, respectively. Each of encryption data 404 and 406 mayinclude an uncertified public/private key pair for each respectivedevice. The public/private key pairs may be asymmetric key pairs such asRivest, Shamir, and Adelman (RSA) keys, Elliptic-curve cryptography(ECC) keys, or keys for some other suitable cryptographic algorithm. Insome embodiments, the access devices 104-1 and 104-2 may be configuredto generate a new public/private key pair for each potential interactionwith a user device (e.g., the user device 102). In other embodiments,the access devices 104-1 and 104-2 may be configured to reuse arespective single public/private key pair to perform variousinteractions with a variety of user devices.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. By way of example, the identification data may include anidentifier of a resource provider (e.g., a merchant, such as“SuperGas”). In some embodiments, the identification informationassociated with the access device 104-1 may further include a deviceidentifier (e.g., “pump 1”). The user device 102 may approach the accessdevice 104-1 to breach a threshold distance from the access device 104-1(e.g., within range of receiving short-range wireless messages of theshort-range wireless communications protocol).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102 unaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface of FIG. 2.

Returning to the FIG. 1, upon presenting the user interface 200 andreceiving confirmation (e.g., an indication that confirmation button 204was selected) that the user intends to establish a connection with“SuperGas, Pump 1,” a connection may be established utilizing anysuitable short-range wireless protocol (e.g., BLE) between theintervening device 106-1 and the user device 102. The user of the userdevice 102 may believe (e.g., based on the text 202 provided in userinterface 200 of FIG. 2) that they are connecting to the access device104-1. However, the user device 102 may actually be connected to thefraudster's device (e.g., intervening device 106-1).

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 may connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 4. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas”). The intervening device 106-2may connect (or otherwise transmit data) via a second BLE connection tothe access device 104-2 at step 5.

In some embodiments, the access device 104-2 may generate interactiondata (e.g., including identification information associated with theaccess device 104-2, an interaction value such as a pre-authorizationamount, etc.) for transmission. However, before transmitting theinteraction data, the access device 104-2 may be configured to generatea digital signature utilizing at least a portion of the interactiondata. FIG. 5 shows a schematic diagram 500 illustrating an exemplarymethod for generating a digital signature, according to someembodiments.

Schematic diagram 500 depicts message data 502. Message data 502 mayinclude any suitable number of data fields corresponding to any suitablecombination of data for establishing a connection and/or performing aninteraction between an access device and/or a user device. By way ofexample, the message data 502 may include a data field 502A. In someembodiments, data field 502A may include an identifier associated with aprovider of an access device (e.g., a merchant, such as “SuperGas” ofthe example of FIG. 4). Message data 502 may additionally, oralternatively, include data field 502B. In some embodiments, data field502B may include a device identifier (e.g., a serial number, anidentifier associated with a particular device of the provider (e.g.,“Pump 4” of the example of FIG. 4). In some embodiments, the messagedata 502 may additionally, or alternatively, include data field 502C. Insome embodiments, data field 502C may correspond to an interactionamount (e.g., a pre-authorization amount, a final purchase price, etc.).In some embodiments, the message data 502 may additionally, oralternatively, include data field 502D. In some embodiments, data field502D may correspond to a location (e.g., a location associated with anaccess device). In some embodiments, the message data 502 mayadditionally, or alternatively, include data field 502E. In someembodiments, data field 502E may correspond to a public key (e.g., apublic key associated with an access device). Any suitable combinationof data fields 504 may be utilized (e.g., by an access device) togenerate digital signature 506. It should be appreciated that the orderof the message data 502 may differ between embodiments. Although notdepicted, in some embodiments (e.g., for messages transmitted from auser device to an access device) data fields may further include a datafield for transmitting payment data.

In some embodiments, the digital signature 506 may be generated (e.g.,by an access device) by hashing any suitable portion of the data fields504. By way of example, the digital signature 506 may be generated byfirst providing data fields 502A and/or 502B as input into a hashingalgorithm to produce a hash value. The produced hash value may then beinput, along with a private key (e.g., a private key associated with theaccess device) to a signing algorithm to produce digital signature 506.Digital signature 506 may be utilized, along with the public keycorresponding to the private key, to verify that any data fields thatwere utilized to produce the digital signature have not been altered. Asa non-limiting example, a receiver of the message data 502, may utilizea public key (e.g., the public key provided in data field 502E) toretrieve a hash value from the digital signature 506. The receiver maythen produce a hash from a predetermined combination of the data fields504 (e.g., the data fields 502A and 502B) to generate an additional hashvalue. The receiver may then compare the hash retrieved from the digitalsignature 506 to the generated hash. If the two hash values match, thereceiver is assured that the message is valid (e.g., unaltered). If thetwo hash value do not match, the receiver may determine that the messageis invalid (e.g., has been altered since original transmission). Itshould be appreciated that the example provided in FIG. 5 isillustrative and not intended to limit the scope of this disclosure. Inother embodiments, any suitable combination of the data fields 504(e.g., all of the data fields 504, more or fewer data fields thanalready described above, etc.) may be utilized to generate the digitalsignature 506, which in turn may be utilized to determine whether or notsuch data has been altered on receipt.

Returning to FIG. 4, the access device 104-2 may generate a digitalsignature at step 6 utilizing at least a portion of the interactiondata. By way of example, the access device 104-2 may utilizeidentification data (e.g., a merchant identifier, a device identifier,etc.) of the interaction data to generate a digital signature in themanner described in FIG. 5. In some embodiments, the digital signaturemay be generated using other interaction data (e.g., location,interaction value, etc.) in addition to the identification data. Theaccess device 104-2 may insert the digital signature, and the public keycorresponding to the private key utilized to generate the digitalsignature, within a message and transmit the message to the user device102.

The intervening device 106-2 may receive the message from the accessdevice 104-2 at step 7 and relay the message to the intervening device106-1 at step 8.

The intervening device 106-1 (and/or the intervening device 106-2) mayalter the interaction data provided by the access device 104-2. As anon-limiting example, the intervening device 106-1 may alter theidentification data to indicate that the interaction data was providedby the access device 104-1 rather than the access device 104-2. Morespecifically, intervening device 106-1 and/or 106-2 may alter theinteraction data associated with “OtherGas, Pump 4” to “SuperGas, Pump1”. This altered interaction data may be relayed to the user device 102at step 9.

At step 10, the user device 102 may be configured to validate thereceived message utilizing the digital signature and the public keyassociated with the access device 104-2 that was received within themessage. By way of example, the public key included in the receivedmessage may be utilized to extract a hash value of the digital signatureincluded in the message. The user device 102 may then calculate anadditional hash value based on a predetermined set of data fields (e.g.,the data fields 502A and 502B of FIG. 5). The user device 102 maycompare the extracted hash value to the calculated hash value.

At step 11, since the hash value don't match due to the data beingchanged, the user device 102 may be configured to determine that themessage is invalid (e.g., altered, or at least the predetermined set ofdata fields were altered) and terminate any further interaction withaccess device 104-2.

FIG. 6 shows a block diagram illustrating another exemplary method 600for preventing a relay attack, according to some embodiments. FIG. 6illustrates a use case in which an access device (e.g., the accessdevice 104-2) digitally signs data utilizing its private key prior totransmission. The public key corresponding to the private key may beincluded in the transmission. If the data is not modified by anintervening device but is merely relayed, the validation of the digitalsignature may pass validation at the user device 102. However, eventhough the message may be determined to be valid (e.g., unaltered) anadditional check of at least some of the data of the message (e.g.,identification data indicating a merchant name/identifier for example)may be performed. By way of example, the identification data of themessage coming from the access device 104-2 may be compared to theidentification received at the initial connection stage to ensure thatthe entity interacting with the user device is the same entity withwhich the user device 102 believes a connection was approved.

In the example depicted in FIG. 6, as in the example of FIG. 4, the userdevice 102 may be configured with encryption data 402. As discussedabove with respect to FIG. 4, the encryption data 402 may include acertificate issued by a certificate authority (not depicted). The accessdevices 104-1 and 104-2 may each be configured to generate encryptiondata 404 and 406, respectively, which individually may include anuncertified public/private key pair for each respective device.

Steps 1-10 of method 600 may be the performed in a similar manner ofsteps 1-10 of method 400 as described above in connection with FIG. 4.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. By way of example, the identification data may include anidentifier of a resource provider (e.g., a merchant, such as“SuperGas”). In some embodiments, the identification data associatedwith the access device 104-1 may further include a device identifier(e.g., “pump 1”). The user device 102 may approach the access device104-1 to breach a threshold distance from the access device 104-1 (e.g.,within range of receiving short-range wireless messages of theshort-range wireless communications protocol).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102 unaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface of FIG. 2.

Upon presenting the user interface 200 and receiving confirmation (e.g.,an indication that confirmation button 204 was selected) that the userintends to establish a connection with “SuperGas, Pump 1,” a connectionmay be established utilizing any suitable short-range wireless protocol(e.g., BLE) between the intervening device 106-1 and the user device102. The user of the user device 102 may believe (e.g., based on thetext 202 provided in user interface 200 of FIG. 2) that they areconnecting to the access device 104-1. However, the user device 102 mayactually be connected to the fraudsters device (e.g., intervening device106-1). The user device 102, in this embodiment, may store at least aportion of the data received in the advertisement message. By way ofexample, the user device 102 may store identification data (e.g.,“SuperGas”) as being indicative of the device to which the user device102 is purportedly connected.

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 may connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 4. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas”). The intervening device 106-2may connect (or otherwise transmit data) via a second BLE connection tothe access device 104-2 at step 5.

In some embodiments, the access device 104-2 may generate interactiondata (e.g., including identification information associated with theaccess device 104-2, an interaction value such as a pre-authorizationamount, etc.) for transmission. However, before transmitting theinteraction data, the access device 104-2 may be configured to generatea digital signature utilizing at least a portion of the interaction datain the manner discussed above in connection with FIGS. 4 and 5.

At step 6, the access device 104-2 may generate a digital signatureutilizing at least a portion of the interaction data. By way of example,the access device 104-2 may utilize identification data (e.g., amerchant identifier, a device identifier, any suitable combination ofthe data fields 504 of FIG. 5, etc.) of the interaction data to generatea digital signature in the manner described in FIG. 5. The access device104-2 may insert the digital signature, and the public key correspondingto the private key utilized to generate the digital signature, within amessage and transmit the message to the user device 102.

The intervening device 106-2 may receive the message from the accessdevice 104-2 at step 7 and relay the message to the intervening device106-1 at step 8. The intervening device 106-1 (and/or the interveningdevice 106-2) may relay the unaltered message the user device 102 atstep 9. It should be appreciated that in the ongoing example, themessage still indicates identification data corresponding to “OtherGas.”

At step 10, the user device 102 may be configured to validate thereceived message utilizing the digital signature and the public keyassociated with the access device 104-2 that was received within themessage. By way of example, the public key included in the receivedmessage may be utilized to extract a hash value of the digital signatureincluded in the message. The user device 102 may then calculate anadditional hash value based on a predetermined set of data fields (e.g.,the data field 502A and 502B of FIG. 5). The user device 102 may comparethe extracted hash value to the calculated hash value.

At step 11, since the hash values may match due to the message databeing unaltered, the user device 102 may be configured to determine thatthe message is valid (e.g., unaltered, or at least the predetermined setof data fields were not altered).

At step 12, the user device may be further configured to determinewhether some portion of the data fields match stored information. By wayof example, the user device 102 may determine whether the identificationdata received in the message (e.g., indicating “OtherGas”) matches theidentification data stored at the user device 102 and associated withthe access device 104-1 (e.g., “SuperGas”) with which the user device102 is supposedly connected. In the ongoing example, the user device 102may determine that the received identification data (e.g., “OtherGas”)does not match the stored identification data associated with theconnection device (e.g., “SuperGas”). Based at least in part on thisdetermination, the user device 102 may be configured to terminate anyfurther interaction with access device 104-2.

FIG. 7 shows a block diagram illustrating yet another exemplary method700 for preventing a relay attack, according to some embodiments. FIG. 7is directed to an example in which the access device 104-1 provides itspublic key in a connection message transmitted to user device 102. Thatsame public key may be used to validate a subsequent message from theaccess device 104-2. In a relay attack, the public key of the connectingdevice would not match the public key of the subsequent message, thismay cause a validation check of the subsequent message to fail at theuser device 102.

In the example depicted in FIG. 7, as described above in connection withFIGS. 4 and 6, the user device 102 may be configured with encryptiondata 402 (e.g., a certificate and/or a certified public/private keypair). The access devices 104-1 and 104-2 may each be configured togenerate and/or store encryption data 404 and 406, respectively. Each ofencryption data 404 and 406 may include an uncertified public/privatekey pair for each respective device. By way of example, encryption data404 may include public key 702 and a private key associated with thepublic key 702.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. By way of example, the identification data may include anidentifier of a resource provider (e.g., a merchant, such as“SuperGas”). In some embodiments, the identification data associatedwith the access device 104-1 may further include a device identifier(e.g., “pump 1”). In the example provided in FIG. 7, the advertisementmessage may further include the public key 702 of encryption data 404.The user device 102 may approach the access device 104-1 to breach athreshold distance from the access device 104-1 (e.g., within range ofreceiving short-range wireless messages of the short-range wirelesscommunications protocol).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102 unaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface 200 of FIG. 2. In some embodiments, the user device102 may store the public key 702 of the encryption data 404 at the userdevice 102.

Upon presenting the user interface 200 and receiving confirmation (e.g.,an indication that confirmation button 204 of FIG. 2 was selected) thatthe user intends to establish a connection with “SuperGas, Pump 1,” theuser device 102 may establish a connection utilizing any suitableshort-range wireless protocol (e.g., BLE) with the intervening device106-1 at step 4. The user of the user device 102 may believe (e.g.,based on the text 202 provided in user interface 200 of FIG. 2) thatthey are connecting to the access device 104-1. However, the user device102 may actually be connected to the fraudster's device (e.g.,intervening device 106-1).

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 may connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 5. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas”). The intervening device 106-2may connect (or otherwise transmit data) via a second BLE connection tothe access device 104-2 at step 6.

In some embodiments, the access device 104-2 may generate interactiondata (e.g., including identification data associated with the accessdevice 104-2, an interaction value such as a pre-authorization amount,etc.) for transmission. However, before transmitting the interactiondata, the access device 104-2 may be configured to generate a digitalsignature utilizing at least a portion of the interaction data asdescribed above in connection with FIGS. 4-7. The access device 104-2may generate a digital signature at step 7 utilizing at least a portionof the interaction data. By way of example, the access device 104-2 mayutilize any suitable portion of the interaction data (e.g., a merchantidentifier and/or a device identifier, a merchant identifier/deviceidentifier/and a location associated with the access device, or anysuitable combination of the data fields 504 of FIG. 5) to generate adigital signature in the manner above. The access device 104-2 mayinsert the digital signature within a message and transmit the messageto the user device 102. In some embodiments, the access device 104-2 may(or may not) insert the public key utilized to generate the digitalsignature within the same message prior to transmitting the message tothe user device 102.

The intervening device 106-2 may receive the message from the accessdevice 104-2 at step 8 and relay the message to the intervening device106-1 at step 9. The intervening device 106-1 may forward the message,unaltered or altered, to the user device 102 at step 10. In someembodiments, the intervening devices 106-1 and/or 106-2 may alter someportion of the message, while in other embodiments, the interveningdevices 106-1 and 106-2 simply relay the message unaltered to the userdevice 102.

At step 11, the user device 102 may be configured to validate thereceived message utilizing the digital signature and the public key 702.By way of example, the public key 702 received at connection may beutilized to extract a hash value of the digital signature included inthe message received at step 10. The user device 102 may then calculatean additional hash value based on a predetermined set of data fields(e.g., the data fields 502A and 502B, the data fields 502A, 502B, and502D, or any suitable combination of the data fields 504 of FIG. 5). Theuser device 102 may compare the extracted hash value to the calculatedhash value.

At step 12, since the hash values do not match (e.g., based at least inpart on the public key 702 being utilized to validate the message andthat the public key 702 does not correspond to the private key used togenerate the digital signature) the user device 102 may determine thatthe message is invalid. This determination may occur regardless ofwhether the message was altered or unaltered. In some embodiments, inaddition, or as an alternative to validation utilizing the digitalsignature, the user device 102 may be configured to compare the publickey 702 to the public key included in the message received at step 10.If the public keys do not match, the user device 102 may be configuredto determine the message is invalid without necessarily validating themessage utilizing the digital signature and hash values as describedabove.

At step 13, in response to determining that the message is invalid, theuser device 102 may terminate any further interaction with the accessdevice 104-2.

FIG. 8 shows a block diagram illustrating yet another exemplary methodfor preventing a relay attack, according to some embodiments. FIG. 8 isdirected to an example in which two intervening device merely relaymessages between access devices and a user device. Because the messagesare not modified, a validation check of the message may indicate thatthe message is valid (e.g., unaltered). However, the user may beprovided a notification which may enable the user to become aware of adiscrepancy between the entity he believed he was connected to and theentity subsequently requesting additional data (e.g., payment data). Theuser may utilize this notification to proceed with canceling theinteraction due to this discrepancy.

In the example depicted in FIG. 8, as described above in connection withFIGS. 4, 6, and 7, the user device 102 may be configured with encryptiondata 402 (e.g., a certificate and/or a certified public/private keypair). The access devices 104-1 and 104-2 may each be configured togenerate and/or store encryption data 404 and 406, respectively. Each ofencryption data 404 and 406 may include an uncertified public/privatekey pair for each respective device.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. By way of example, the identification data may include anidentifier of a resource provider (e.g., a merchant, such as“SuperGas”). In some embodiments, the identification data associatedwith the access device 104-1 may further include a device identifier(e.g., “pump 1”). The user device 102 may approach the access device104-1 to breach a threshold distance from the access device 104-1 (e.g.,within range of receiving short-range wireless messages of theshort-range wireless communications protocol).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102 unaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface 200 of FIG. 2.

Returning to the FIG. 8, upon presenting the user interface 200 andreceiving confirmation (e.g., an indication that confirmation button 204of FIG. 2 was selected) that the user intends to establish a connectionwith “SuperGas, Pump 1,” a connection may be established utilizing anysuitable short-range wireless protocol (e.g., BLE) between theintervening device 106-1 and the user device 102. The user of the userdevice 102 may believe (e.g., based on the text 202 provided in userinterface 200 of FIG. 2) that they are connecting to the access device104-1. However, the user device 102 may actually be connected to thefraudster's device (e.g., intervening device 106-1).

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 may connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 4. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas”). The intervening device 106-2may connect (or otherwise transmit data) via a second BLE connection tothe access device 104-2 at step 5.

In some embodiments, the access device 104-2 may generate interactiondata (e.g., including identification information associated with theaccess device 104-2, an interaction value such as a pre-authorizationamount, etc.) for transmission. However, before transmitting theinteraction data, the access device 104-2 may be configured to generatea digital signature utilizing at least a portion of the interaction dataas described above in connection with FIGS. 4-7. The access device 104-2may generate a digital signature at step 6 utilizing at least a portionof the interaction data. By way of example, the access device 104-2 mayutilize identification data (e.g., a merchant identifier, a deviceidentifier) and (in some cases) a location associated with the accessdevice to generate a digital signature in the manner described in FIG.5. The access device 104-2 may insert the digital signature, and thepublic key corresponding to the private key utilized to generate thedigital signature, within a message and transmit the message to the userdevice 102.

The intervening device 106-2 may receive the message from the accessdevice 104-2 at step 7 and relay the message to the intervening device106-1 at step 8. The intervening device 106-1 may forward the message,unaltered, to the user device 102 at step 9.

At step 10, the user device 102 may be configured to validate thereceived message utilizing the digital signature and the public keyassociated with the access device 104-2 that was received within themessage. By way of example, the public key included in the receivedmessage may be utilized to extract a hash value of the digital signatureincluded in the message. The user device 102 may then calculate anadditional hash value based on a predetermined set of data fields (e.g.,the data fields 502A and 502B, the data fields 502A, 502B, and 502D, orany suitable combination of the data fields 504 of FIG. 5). The userdevice 102 may compare the extracted hash value to the calculated hashvalue.

At step 11, since the hash values match due to the data being unaltered,the user device 102 may be configured to determine that the message isvalid (e.g., unaltered, or at least the predetermined set of data fieldswere unaltered). As a result of this determination, a user interface(e.g., the user interface 300 of FIG. 3) may be presented at the userdevice 102 to illicit confirmation from the user with respect to anintent to interact with the access device 104-2. It may be the case thatbecause the user was presented with information (e.g., “SuperGas”) atconnection, he may realize that the data now presented (e.g.,“OtherGas”) is associated with a different access device (e.g., accessdevice 104-2) than the access device (e.g., access device 104-1) withwhich he believes he's connected. The user may indicate (e.g., viaselection of the cancellation button 304 of FIG. 3) that he does notintend to interact with access device 104-2.

At step 12, although the message was determined to be valid, the userdevice 102 may terminate any further interaction with the access device104-2 based at least in part on receiving the indication that the userdoes not intend to interact with access device 104-2.

FIG. 9 shows a block diagram illustrating still one further exemplarymethod 900 for preventing a relay attack, according to some embodiments.FIG. 9 is directed to an example in which a user device (e.g., the userdevice 102) falsely believes connection has been made with access device104-1 (e.g., associated with “SuperGas”) but mistakenly authorizes asubsequent interaction with access device 104-2 (e.g., “OtherGas”)because, despite being provided a notification, the user may not havenoticed a discrepancy between the purported connected access device andthe access device requesting the subsequent interaction. In this usecase, the user device 102 may digitally sign data going back to accessdevice 104-2. Upon receipt, access device 104-2 may check a public keyof the message (e.g., the public key of the access device 104-2previously sent to the user device and then digitally signed by userdevice). If the public key included in the message is same public key asheld by access device 104-2 then interaction may be deemed valid. Ifvalid, at least a portion of the received data may be sent to a resourceprovider to conduct a traditional authorization request process. Ifhowever, the message is invalid, the access device 104-2 may beconfigured to cease processing.

In the example depicted in FIG. 9, the user device 102 may be configuredwith encryption data 402. As discussed above with respect to FIG. 4, theencryption data 402 may include a certificate issued by a certificateauthority (not depicted). The access devices 104-1 and 104-2 may each beconfigured to generate encryption data 404 and 406, respectively. Eachof encryption data 404 and 406 may include an uncertified public/privatekey pair for each respective device.

At step 1, access device 104-1 (e.g., located at gas station “SuperGas”at Pump 1) may transmit an advertisement message (e.g., via ashort-range wireless protocol such as BLE). The advertisement messagemay at least include identification data associated with the accessdevice 104-1. By way of example, the identification data may include anidentifier of a resource provider (e.g., a merchant, such as“SuperGas”). In some embodiments, the identification data associatedwith the access device 104-1 may further include a device identifier(e.g., “pump 1”). The user device 102 may approach the access device104-1 to breach a threshold distance from the access device 104-1 (e.g.,within range of receiving short-range wireless messages of theshort-range wireless communications protocol).

At step 2, an intervening device 106-1, operated by a first fraudster,may intercept the advertisement message and relay the message to theuser device 102 unaltered.

At step 3, the user device 102 may receive the advertisement message anddisplay one or more user interfaces for confirming a connection with theaccess device 104-1. By way of example, the user device 102 may presentthe user interface of FIG. 2.

Upon presenting the user interface 200 and receiving confirmation (e.g.,an indication that confirmation button 204 was selected) that the userintends to establish a connection with “SuperGas, Pump 1,” a connectionmay be established utilizing any suitable short-range wireless protocol(e.g., BLE) between the intervening device 106-1 and the user device102. The user of the user device 102 may believe (e.g., based on thetext 202 provided in user interface 200 of FIG. 2) that they areconnecting to the access device 104-1. However, the user device 102 mayactually be connected to the fraudster's device (e.g., interveningdevice 106-1).

Once the connection between the intervening device 106-1 and the userdevice 102 is established, the intervening device 106-1 may connect (orotherwise transmit data), via any suitable wired and/or wirelessconnection, to an accomplice's second fraudulent device (e.g.,intervening device 106-2) at step 4. The intervening device 106-2 can belocated at, for example, another access device (e.g., an access devicelocated at another gas station “OtherGas”). The intervening device 106-2may connect (or otherwise transmit data) via a second BLE connection tothe access device 104-2 at step 5.

In some embodiments, the access device 104-2 may generate interactiondata (e.g., including identification information associated with theaccess device 104-2, an interaction value such as a pre-authorizationamount, etc.) for transmission. However, before transmitting theinteraction data, the access device 104-2 may be configured to generatea digital signature utilizing at least a portion of the interaction datain the manner discussed above in connection with FIGS. 4-8.

At step 6, the access device 104-2 may generate a digital signatureutilizing at least a portion of the interaction data. By way of example,the access device 104-2 may utilize any suitable portion of theinteraction data (e.g., a merchant identifier, a device identifier, anysuitable combination of the data fields 504 of FIG. 5, etc.) to generatea digital signature in the manner described above. The access device104-2 may insert the digital signature, and the public key correspondingto the private key utilized to generate the digital signature, within amessage and transmit the message to the user device 102.

The intervening device 106-2 may receive the message from the accessdevice 104-2 at step 7 and relay the message to the intervening device106-1 at step 8. The intervening device 106-1 (and/or the interveningdevice 106-2) may relay the unaltered message to the user device 102 atstep 9. It should be appreciated that in the ongoing example, themessage still indicates identification data corresponding to “OtherGas.”

At step 10, the user device 102 may be configured to validate thereceived message utilizing the digital signature and the public keyassociated with the access device 104-2 that was received within themessage. By way of example, the public key included in the receivedmessage may be utilized to extract a hash value of the digital signatureincluded in the message. The user device 102 may then calculate anadditional hash value based on a predetermined set of data fields (e.g.,the data field 502A and 502B of FIG. 5). The user device 102 may comparethe extracted hash value to the calculated hash value.

At step 11, since the hash values may match due to the message databeing unaltered, the user device 102 may be configured to determine thatthe message is valid (e.g., unaltered, or at least the predetermined setof data fields were not altered). One or more user interfaces (e.g., theuser interface 300 of FIG. 3 may be provided at the user device. Theuser may not recognize that the text 302 indicates an interaction withan access device (e.g., the access device 104-2) that differs from theaccess device (e.g., the access device 104-1) to which the user believesis connected to the user device 102. As a result, the user may confirmthe interaction at step 12.

At step 13, in response to receiving an indication that the userconfirmed the interaction with access device 104-2, the user device 102may be configured to provide payment data and the encryption data 402(e.g., a certificate issued by a certificate authority, not shown). Insome embodiments, the payment data included in the message by the userdevice 102 may be in the form of a token and/or an encrypted value whichis decryptable by the receiving access device 104-2. The user device 102may include some portion of the interaction data originally provided bythe access device 104-2 in the message received at step 9. By wayexample, the user device 102 may include the identification dataassociated with the access device (e.g., a merchant identifier and/or adevice identifier) along with the public key provided in the messagereceived at step 9 and associated with the access device 104-2. In someembodiments, the user device 102 may be configured to generate a digitalsignature utilizing any suitable message data (e.g., the identificationdata, the public key associated with the access device 104-2, thepayment data, the encryption data 402, or any suitable combination ofthe above and/or the data fields 5024 of FIG. 5).

The intervening device 106-1 may receive the message from the userdevice and relay the message to the intervening device 106-2 at step 14.The intervening device 106-2 may in turn relay the message to accessdevice 104-2.

At step 16, the access device 104-2 may be configured to validate themessage received utilizing a public key associated with the user device102. By way of example, a public key associated with the certificateauthority that issued the certificate contained in the message receivedat step 15 may be retrieved from local memory of the access device104-2. The public key of the certificate authority may be utilized toretrieve the public key associated with the user device 102 from thecertificate. The access device 104-2 may be configured to utilize thepublic key associated with user device 102 to validate the messagereceived at step 15.

By way of example, the access device 104-2 may be configured to utilizethe public key associated with the user device 102 to retrieve a hashvalue from the digital signature of the message received at step 15. Theaccess device 104-2 may then generate an additional hash value utilizinga predetermined hashing algorithm and a predetermined set of data fieldsof the message received at step 15. By way of example, the additionalhash value may be generated by providing the hashing algorithm as inputany suitable combination of the identification data of the message, apublic key included in the message, and/or the payment data included inthe message. Once generated, the resultant hash value may be compared tothe hash value retrieved from the digital signature. If the hash valuesdo not match, the access device 104-2 may be configured to terminate theinteraction and to perform no further processing of the payment data.

If the hash values match, the access device 104-2 may be configured toproceed as the match may indicate that not only was the messageunaltered, but the correct public key associated with the access device104-2 was utilized (e.g., by the user device 102) to validate themessage initially transmitted at step 7. In some embodiments, the accessdevice 104-2 may proceed by generating an authorization request messagewhich may then be transmitted to a resource provider computer (e.g., theresource provider computer 1230 of FIG. 12) as part of an traditionalprocess for authorizing a payment transaction. A flow describing theprocess for authorizing a payment transaction is discussed in furtherdetail with respect to FIG. 12. If the authorization request is granted,the access device 104-2 may enable access to a good and/or service(e.g., gas managed by the access device 104-2) to the user device 102.

The example provided in FIG. 9 illustrates how the disclosed techniquescan successfully prevent a relay attack. A successful relay attack couldbe conducted only if data communicated between the user device 102 andthe access device 104-2 is unaltered. In practice, most users wouldrecognize a discrepancy between the merchant at which they are located(e.g., SuperGas) and the merchant for whom they are being asked forconsent to pay (e.g., OtherGas). Even if the user inadvertently consentsto pay, the signature verification would fail at the access device104-2, [0121] FIG. 10 shows a block diagram of an exemplary user device1002 according to an embodiment of the invention. User device 1002 maybe an example of user device 102 of FIGS. 1, 4, and 6-9. In someembodiments, user device 1002 may include circuitry that is used toenable certain device functions, such as telephony. The functionalelements responsible for enabling those functions may include aprocessor 1002B that can execute instructions that implement thefunctions and operations of the device. Processor 1002B may access thememory 1002F (or another suitable data storage region or element) toretrieve instructions or data used in executing the instructions, suchas provisioning scripts and mobile applications. Data input/outputelements 1002D, such as a keyboard or touchscreen, may be used to enablea user to operate the user device 1002 and input data. Data input/outputelements may also be configured to output data (via a speaker of thedevice, for example). Display 1002C may also be used to output data to auser. Communications element 1002E may be used to enable data transferbetween user device 1002 and a wired or wireless network (via antenna1002G, for example) to assist in connectivity to the Internet or othernetwork, and enabling data transfer functions. In some embodiments, thecommunication element 1002E may utilize a short-range wirelesscommunications protocol (e.g., BLE).

In some embodiments, user device 1002 may also include contactlesselement interface to enable data transfer between contactless element(not shown) and other elements of the device, where contactless elementmay include a secure memory and a near field communications datatransfer element (or another form of short range communicationstechnology). A cellular phone or similar device is an example of a userdevice 1002 that may be used in accordance with embodiments of thepresent invention. However, other forms or types of devices may be usedwithout departing from the underlying concepts of the invention. Forexample, the user device 1002 may alternatively be in the form of apayment card, a key fob, a PDA, a tablet computer, a net book, a laptopcomputer, a smart watch, an automobile with remote capabilities, etc.

The memory 1002F may comprise an application 1002H and/or any othersuitable module or data. For example, in some embodiments, the memory1002F may include signing module 10021, validation module 1002J, and/orencryption data 1002K. The user device 1002 may have any number ofmobile applications installed or stored on the memory 1002F and is notlimited to that shown in FIG. 10. The memory 1002F may also comprisecode, executable by the processor 1002B for implementing the methodsdiscussed herein.

The application 1002H may be in any suitable form. By way of example,the application 1002H may be an application that may be utilized tointeract with an access device (e.g., the access device 104-1 of FIG. 1,the access device 1102 of FIG. 11, etc.). In some embodiments, theapplication 1002H may be an application configured to provide anysuitable user interfaces (e.g., the user interfaces 200 and 300 of FIGS.2 and 3, respectively) or any suitable user interface configured tocollect data and/or confirm interaction between a user device 1002 andan access device. In some embodiments, the application 1002H may beutilized to perform a transaction for a good and/or a service such asexchanging payment data and/or interaction data (e.g., identificationdata, interaction value, a public key, location, device information,etc.) with an access device to obtain fuel (or another good and/orservice) and/or access to a resource (e.g., as in access to a buildingas described below with respect to FIG. 13). In some embodiments, theapplication 1002H (or another suitable module) may be configured tocause the processor 1002B to perform operations and/or present anysuitable user interfaces for establishing a connection (e.g., a BLEconnection) with one or more other devices (e.g., an access device, anintervening device, etc.). The application 1002H (or another suitablemodule) may be further configured to cause the processor 1002B toperform operations and/or present any suitable interface for confirmingan interaction with one or more other devices (e.g., an access device,an intervening device, etc.).

In some embodiments, the application 1002H may be configured to transmitand/or receive any suitable message to/from an access device and/or anintervening device. In some embodiments, these messages may betransmitted and/or received via a BLE and/or other suitable short-rangewireless communications protocol. The application 1002H may beconfigured to cause the processor 1002B to stimulate the functionalityof the signing module 10021 prior to transmission of a message and/or tostimulate the functionality of the validation module 1002J upon receiptof a message.

The signing module 10021 may be configured with code that, when executedby the processor 1002B may cause the processor 1002B to perform anysuitable operations for generating a digital signature and transmittinga message that at least includes the digital signature. By way ofexample, the signing module 10021 may be configured to cause theprocessor 1002B to hash one or more data fields of message data (e.g.,identification data associated with the user device 1002, identificationdata associated with an access device, one or more locations associatedwith the user device 1002 and/or the access device, an interactionvalue, a public key of an access device, a certificate of the userdevice 1002, and/or the like) to produce a hash value. In someembodiments, the signing module 10021 may be configured to cause theprocessor 1002B to digitally sign the hash value with a private keyassociated with the user device 1002. Once generated, the digitalsignature may be inserted into a message (e.g., along with one or moreother data fields such as identification data associated with the userdevice 1002, identification data associated with an access device, oneor more locations associated with the user device 1002 and/or the accessdevice, the interaction value, a public key of an access device, acertificate of the user device 1002, and/or the like) and transmitted toan access device. In some embodiments, the signing module 10021 mayoperate as part of the application 1002H.

The validation module 1002J may be configured with code that, whenexecuted by the processor 1002B may cause the processor 1002B to performany suitable operations for validating a message. In some embodiments,the validation module 1002J may be configured to cause the processor1002B to receive a message including a public key of an access device.The validation module 1002J may, in some embodiments, store the receivedpublic key within the memory 1002F for subsequent use. In someembodiments, the validation module 1002J may be configured to cause theprocessor 1002B to receive a message including a digital signature(e.g., a digital signature generated by an access device utilizing aprivate key associated with the access device). In some embodiments, thereceived message may also include a public key associated with an accessdevice. The validation module 1002J may cause the processor 1002B toutilize the public key (e.g., either received in the message includingthe digital signature or utilizing the stored public key received in aprevious message) to validate the received message.

By way of example, the validation module 1002J may be configured tocause the processor 1002B to utilize the stored or received public keyto retrieve a hash value from the digital signature. The validationmodule 1002J may further cause the processor 1002B to hash one or moredata fields of the received message (e.g., identification dataassociated with the user device 1002, identification data associatedwith an access device, one or more locations associated with the userdevice 1002 and/or the access device, an interaction value, a public keyof an access device, a certificate of the user device 1002, and thelike) to produce an additional hash value. In some embodiments, thevalidation module 1002J may be configured to cause the processor 1002Bto compare the hash value retrieved from the digital signature with thecalculated hash value. If the hash values match, the validation module1002J may stimulate the application 1002H (or another suitable module)to perform operations (e.g., transmit a message including at least aportion of the received message data to another device such as aresource provider computer 1230 of FIG. 12).

In some embodiments, if the hash values match, the validation module1002J may determine that the message is valid (e.g., unaltered). In someembodiments, the validation module 1002J may be configured to cause theprocessor 1002B to conduct a further determination as to whether alocation of the valid message is within a threshold distance of alocation associated with the user device 1002. In these examples, thevalidation module 1002J may retrieve a location associated with the userdevice 1002 from, for example, a global positioning system component ofthe 1002 (e.g., an example of the data input/output elements 1002D). Instill further embodiments, the validation module 1002J may, upondetermining that the message is valid (e.g., based on the comparison ofthe retrieved hash and the calculated hash), perform additionaloperations of comparing an stored identifier associated with an accessdevice to which the user device 1002 has supposedly connected, toidentification data of the received message that is associated with thetransmitting device (e.g., an access device). In some embodiments, thevalidation module 1002J may terminate an interaction and perform nofurther processing with a transmitting device if the message isdetermined to be invalid (e.g., altered, based at least in part on thecomparison of the retrieved hash and the calculated hash), and/or thelocations are not within a threshold distance of one another, and/or ifthe stored identifier does not match the identification data included inthe received message. In some embodiments, the validation module 1002Jmay operate as part of the application 1002H.

In some embodiments, the validation module 1002J (e.g., upon determiningthat the message is valid, and/or the locations are within thepredetermined distance of one another, and/or that the stored identifiermatches identification data included in the message) may be configuredto trigger the application 1002H to present a user interface at thedisplay 1002C to illicit confirmation from the user of the user device1002 that he desires to interact with the transmitting device (e.g., theaccess device indicated in the message). Upon receiving an indication ofconfirmation, the application 1002H may be configured to cause theprocessor 1002B to execute code associated with the signing module 10021described above to transmit a message that may include a digitalsignature generated by the signing module 10021 as described above.

The encryption data 1002K may be in the form of a certificate providedby a certificate authority (e.g., the processing network computer 1250of FIG. 12 or any suitable certifying authority). The encryption data1002K may further include a public/private key issued by the certificateauthority and provisioned to the user device 1002. The certificate, insome embodiments, may be digitally signed with a private key associatedwith the certificate authority. A public key of the certificateauthority may be distributed to one or more access devices. In someembodiments, the certificate may include a public key associated withthe user device 1002 and/or any suitable identification data. Thecertificate may be digitally signed by the certificate authority suchthat the public key distributed to an access device may be utilized toretrieve the public key associated with the user device 1002 from thecertificate.

An example of an access device 1102 according to an embodiment of theinvention, is shown in FIG. 10. Access device 1102 may be an example ofthe access device 104-1 and/or 104-2 of FIG. 1. In some embodiments,access device 1102 may include circuitry that is used to enable certaindevice functions, such as telephony. The functional elements responsiblefor enabling those functions may include a processor 1102B that canexecute instructions that implement the functions and operations of thedevice. Processor 1102B may access the memory 1102F (or another suitabledata storage region or element) to retrieve instructions or data used inexecuting the instructions, such as provisioning scripts and mobileapplications. Data input/output elements 1102D, such as a keyboard ortouchscreen, may be used to enable a user to operate the access device1102 and input data. Data input/output elements may also be configuredto output data (via a speaker of the device, for example). Display 1102Cmay also be used to output data to a user. Communications element 1102Emay be used to enable data transfer between access device 1102 and awired or wireless network (via antenna 1102G, for example) to assist inconnectivity to the Internet or other network, and enabling datatransfer functions. In some embodiments, the communication element 1102Emay utilize a short-range wireless communications protocol (e.g., BLE).

In some embodiments, access device 1102 may also include contactlesselement interface to enable data transfer between contactless element(not shown) and other elements of the device, where contactless elementmay include a secure memory and a near field communications datatransfer element (or another form of short range communicationstechnology). A point of sale terminal is an example of an access device1102 that may be used in accordance with embodiments of the presentdisclosure. However, other forms or types of devices may be used withoutdeparting from the underlying concepts of the invention.

The memory 1102F may comprise a data processing module 1102H and/or anyother suitable module or data. For example, in some embodiments, thememory 1102F may further include signing module 1102I, validation module1102J, and/or encryption data 1102K. The memory 1102F may also comprisecode, executable by the processor 1102B for implementing the methodsdiscussed herein.

The encryption data 1102K may be in the form of a public/private keypair generated by the access device 1102. The public/private key pairmay be generated at any suitable time and stored in memory 1102F forsubsequent use. In some embodiments, a new public/private key pair maybe generated to correspond to a particular interaction with anotherdevice (e.g., a user device, an intervening device, etc.) such that aunique public/private key pair may correspond a particular messageexchange. In other embodiments, the same public/private key pair may beutilized with any suitable message exchange with any suitableinteracting device (e.g., a user device and/or an intervening device).

The data processing module 1102H may be in any suitable form. In someembodiments, the data processing module 1102H may be configured withcode that, when executed by the processor 1102B, cause the processor1102B to send and/or receive messages (e.g., to and/or from a userdevice and/or an intervening device). In some embodiments, the dataprocessing module 1102H may be configured to transmit messages (e.g.,advertisements) indicating at least identification data such as one ormore identifiers of the access device 1102. In some embodiments, thedata processing module 1102H may be configured to cause the processor1102B to include a public key associated with the access device 1102 asretrieved from the encryption data 1102K. The data processing module1102H may include the public key in any suitable message transmission(e.g., an advertisement message, an interaction request message, etc.).In some embodiments, the data processing module 1102H may be configuredto stimulate the functionality of the signing module 1102I to generate adigital signature from one or more message data fields of a message tobe transmitted. In some embodiments, the data processing module 1102Hmay be configured to stimulate the functionality of the validationmodule 1102J based at least in part on receiving a message from a device(e.g., a user device and/or an intervening device).

In general, the data processing module 1102H may be configured totransmit and/or receive any suitable message to/from an access deviceand/or an intervening device. In some embodiments, these messages may betransmitted and/or received via a BLE and/or other suitable short-rangewireless communications protocol. The data processing module 1102H maybe further configured to cause the processor 1102B to stimulate anysuitable functionality of the signing module 1102I and/or the validationmodule 1102J to perform the methods discussed herein.

The signing module 1102I may be configured with code that, when executedby the processor 1102B may cause the processor 1102B to perform anysuitable operations for generating a digital signature and transmittinga message that at least includes the generated digital signature. By wayof example, the signing module 1102I may be configured to cause theprocessor 1102B to hash one or more data fields of a message (e.g.,identification data associated with the access device 1102, a locationassociated with the access device 1102, an interaction value, a publickey of an access device, and/or the like) to produce a hash value. Insome embodiments, the signing module 1102I may be configured to causethe processor 1102B to digitally sign the hash value with a private keyassociated with the access device 1102. Once generated, the digitalsignature may be inserted into a message (e.g., along with one or moreother data fields such as identification information associated with theaccess device 1102, identification information associated with an accessdevice, a location associated with the access device 1102, transactioninformation, a public key of an access device 1102, and/or the like) andtransmitted to another device (e.g., the user device 102 of FIG. 1, theintervening device 106-1 of FIG. 1, etc.).

The validation module 1102J may be configured with code that, whenexecuted by the processor 1102B may cause the processor 1102B to performany suitable operations for validating a received message. In someembodiments, the validation module 1102J may be configured to cause theprocessor 1102B to receive a message including a digital signaturepurportedly generated by a user device (e.g., utilizing a private keyassociated with the user device 102). The message may further include acertificate associated with the user device 102 and issued by acertificate authority. In some embodiments, the access device 1102 maystore a public key associated with the certificate authority withinencryption data 1102K. Upon retrieving, the public key of thecertificate authority, the validation module 1102J may be configured toutilize the public key of the certificate authority to retrieve a publickey associated with the user device from the received certificate. Thevalidation module 1002J may cause the processor 1002B to utilize thepublic key associated with the user device and retrieved from thecertificate to validate the digital signature of the received message.

By way of example, the validation module 1102J may be configured tocause the processor 1102B to utilize the public key of the user deviceto retrieve a hash value from the digital signature. The validationmodule 1102J may further cause the processor 1102B to hash one or moredata fields of the received message (e.g., identification informationassociated with the access device 1102, identification informationassociated with the user device 102, payment data and/or transactioninformation, a certificate of the user device 102, and the like) toproduce an additional hash value. In some embodiments, the validationmodule 1102J may be configured to cause the processor 1102B to comparethe hash value retrieved from the digital signature with the calculatedhash value. If the hash values match, the validation module 1102J maystimulate the data processing module 1102H (or another suitable module)to perform operations (e.g., transmit a message including at least aportion of the received message data to another device such as aresource provider computer 1230 of FIG. 12).

In some embodiments, if the hash values match, the validation module1102J may determine that the message is valid (e.g., unaltered). In someembodiments, the validation module 1102J may be configured to cause theprocessor 11026 to retrieve a public key of the access device, utilizedto transmit a message to the user device 102, from the message receivedfrom a user device (or from an intervening device). The validationmodule 1102J may be configured to cause the processor 1102B to determinewhether the public key of the access device included in the receivedmessage matches the public key of the access device stored in theencryption data 1102K that was utilized in a past transmission to theuser device. If the public keys match, the validation module 1102J maybe configured to cause the processor 11026 to determine that the messageis valid (e.g., unaltered) and that a previously transmitted messagethat resulted in the received message was validated by a user device(e.g., user device 102) utilizing the correct public key (e.g., thepublic key stored in the encryption data 1102K that was associated withthe previously transmitted message). In some embodiments, the validationmodule 1102J may terminate an interaction and perform no furtherprocessing with a transmitting device if the message is determined to beinvalid (e.g., altered, based at least in part on the comparison of theretrieved hash and the calculated hash), and/or the public key of thereceived message does not match the public key stored in encryption data1102K and associated with a previous message transmission to the userdevice 102.

The above-described systems and methods for preventing relay attacks canbe used in any suitable transaction or interaction process. For example,they can be used in payment processes or access transactions. Theseexamples are described in further detail in connection with FIGS. 12 and13 below.

FIG. 12 shows a block diagram 1200 of a transaction processing systemthat can use a user device 102. FIG. 12 shows a user 1206 that canoperate a user device 1210 (e.g., an example of the user device 102 ofFIGS. 1-10, the user device 1002 of FIG. 10, etc.). The user 1206 mayuse the user device 1210 to pay fora good or service at a resourceprovider such as a merchant. The merchant may operate a resourceprovider computer 1230 and/or an access device 1220 (e.g., an example ofthe access device 104-1 and/or access device 1102 of FIG. 1-10). Themerchant may communicate with an authorizing entity computer 1260operated by an issuer, via a transport computer 1240 operated by anacquirer and a processing network 1250 such a payment processingnetwork.

The payment processing network may include data processing subsystems,networks, and operations used to support and deliver authorizationservices, exception file services, and clearing and settlement services.An exemplary payment processing network may include VisaNet™. Paymentprocessing networks such as VisaNet™ are able to process credit cardtransactions, debit card transactions, and other types of commercialtransactions .VisaNet™, in particular, includes a VIP system (VisaIntegrated Payments system) which processes authorization requests and aBase II system which performs clearing and settlement services. Thepayment processing network may use any suitable wired or wirelessnetwork, including the Internet.

A typical payment transaction flow using a user device 1210 at an accessdevice 1220 (e.g., POS location) can be described as follows. A user1206 presents his user device 1210 to an access device 1220 to pay foran item or service. The user device 1210 and the access device 1220 mayinteract via a BLE communications protocol. In some embodiments, data(e.g., identification information, a public key, a certificate, locationinformation, interaction data, etc.) may be exchanged between the userdevice 1210 and the access device 1220. Data transmitted from the accessdevice 1220 to the user device 1210 may be digitally signed in themanner described above by the access device 1220 and verified by theuser device 1210. Similarly, data transmitted from the user device 1210may be digitally signed in the manner described above by the user device1210 and verified by the access device 1220. If the interaction isallowed and the message data exchanged between the devices is verifiedas being unaltered, data related to the interaction (e.g.,identification data of the access device 1220, identification data ofthe user device 1210, payment information, message data 502 of FIG. 5,or any suitable data) may be transmitted to the resource providercomputer 1230.

The resource provider computer 1230 may receive this information fromthe access device 1220 via an external communication interface. Theresource provider computer 1230 may then generate an authorizationrequest message that includes the information received from the accessdevice 1220 and electronically transmits this information to a transportcomputer 1240. The transport computer 1240 may then receive, process,and forward the authorization request message to a processing network1250 for authorization.

In general, prior to the occurrence of a credit or debit-cardtransaction, the processing network 1250 has an established protocolwith each issuer on how the issuer's transactions are to be authorized.In some cases, such as when the transaction amount is below a thresholdvalue, the processing network 1250 may be configured to authorize thetransaction based on information that it has about the user's accountwithout generating and transmitting an authorization request message tothe authorizing entity computer 1260. In other cases, such as when thetransaction amount is above a threshold value, the processing network1250 may receive the authorization request message, determine the issuerassociated with the user device 1210, and forward the authorizationrequest message for the transaction to the authorizing entity computer1260 for verification and authorization. Once the transaction isauthorized, the authorizing entity computer 960 may generate anauthorization response message (that may include an authorization codeindicating the transaction is approved or declined) and transmit thiselectronic message via its external communication interface toprocessing network 1250. The processing network 1250 may then forwardthe authorization response message to the transport computer 1240, whichin turn may then transmit the electronic message to comprising theauthorization indication to the resource provider computer 1230, andthen to the access device 1220. The access device 1220 may provideaccess to the goods and/or services based at least in part on thereceipt of the authorization response message (e.g., receiving anauthorization response message that indicates the transaction wasapproved).

At the end of the day or at some other suitable time interval, aclearing and settlement process between the resource provider computer1230, the transport computer 1240, the processing network 1250, and theauthorizing entity computer 1260 may be performed on the transaction.

FIG. 13 shows a block diagram of a building access system. FIG. 13 showsa user device 1310 (e.g., user device 102 of FIG. 1) operated by a user1306. The user device 1310 may be been provisioned with certificate asdescribed above. The user device 1310 can interact with the accessdevice 1320 (e.g., an example of the access device 104-1 of FIG. 1) andpass access data to the access device 1320. The access device 1320 maybe configured to generate a public/private key. An advertisement and/orany suitable message data (e.g., an identifier of the access device1320, a location of the access device 1320, interaction data, etc.)transmitted by the access device 1320 may be hashed and the resultanthash value signed using the private key. The access device 1320 mayprovide the public key and the digital signature to the user device 1310in the same message or different message. The user device 1310 mayutilize the public key provided (or a public key received from anotheraccess device in the case of relay attack) to validate the message. Ifthe message is invalid, the user device 1310 may terminate theinteraction with access device 1320. If the message is valid, the userdevice 1310 may utilize additional message data (e.g., a location of theaccess device 1320) to perform a distance check and terminateinteraction if the distance of the user device 1310 is outside athreshold distance to the location of the access device 1320). If themessage is valid, the user of the user device 1310 may be presented withan option to confirm interaction with the access device 1320. Ifconfirmed, the user device 1310 may transmit a message back to theaccess device 1320.

In some embodiments, the message data of the message transmitted by theuser device 1310 to the access device 1320 may include the certificateassociated with the user device 1310, an identifier of the access device1320, and the public key utilized to validate the originally receivedmessage. In some embodiments, the identifier of the access device 1320and the public key may be hashed and digitally signed utilizing aprivate key associated with the user device 1310. Upon receipt, or atany suitable time, the access device 1320 may utilize the public keyassociated with a certifying authority that issued the certificate toretrieve the public key of the user device 1310 from the certificate.Utilizing the retrieved public key, the access device 1320 may validatethe message utilizing the digital signature provided by the user device1310. As part of validation, the access device 1320 may verify that itspublic key was utilized by the user device 1310 to validate theoriginally transmitted message based at least in part on determiningthat the public key provided in the message was unaltered (e.g., asdeterminable utilizing the digital signature of the message) and thatthe provided public key matches the public key stored by the accessdevice 1320. If the access device 1320 determines that the message datareceived from the user device 1310 is valid, the access device 1320 maythen proceed to let the user 1306 enter the building 1330. If, however,the access device 1320 determines that the wrong public key was used byuser device 1310 for validation, or any of the message data was altered(e.g., as determinable using the digital signature), the access device1320 may terminate interaction with user device 1310, and the user 1306may not be given access to the building 1330.

Technical Benefits

Embodiments of the invention provide for a number of advantages. Forexample, by configuring the disclosed access devices to generate theirown public/private keys, the system may provide enhanced validationfunctionality without incurring additional key maintenance overhead of acertificate authority. Utilizing the various methods disclosed herein,the user device 102 may be configured to validate interaction data froman interacting device (e.g., an access device) utilizing a digitalsignature and a public key. Through this validation, the user device 102may be configured to determine when the message has been altered and maybe configured to automatically reject and/or terminate interaction withan access device. These techniques may ensure that the user device 102does not provide payment information to an intervening device. Even ifone or more intervening devices were to intercept messages and relaythem to the user device 102, the techniques disclosed herein enable theuser to detect that data is being received from a device other than thedevice to which the user confirmed connection. The user may be providedthe ability to cancel and/or terminate the interaction. Even when theuser may not recognize the discrepancy, the user device 102 maydigitally sign its interaction data (e.g., including its payment data)when transmitting data back to an access device (e.g., potentiallythough one or more intervening devices unknowingly). The receivingaccess device may then verify the data within the message utilizing thepublic key associated with the user device to ensure that 1) the messagewas unaltered, and 2) that the correct public key associated with theaccess device was utilized to validate the original message transmittedto the user device. In this manner, data security is enhanced butpreventing relay attacks and/or man in the middle attacks that wouldotherwise enable a fraudster to gain access to sensitive information(e.g., payment data) for fraudulent purposes.

It should be understood that the present invention as described abovecan be implemented in the form of control logic using computer softwarein a modular or integrated manner. Based on the disclosure and teachingsprovided herein, a person of ordinary skill in the art will know andappreciate other ways and/or methods to implement the present inventionusing hardware and a combination of hardware and software. Any of theabove mentioned entities may operate a computer that is programmed toperform the functions described herein.

Any of the software components, processes or functions described in thisapplication may be implemented as software code to be executed by aprocessor using any suitable computer language such as, for example,Java, C++ or Perl using, for example, conventional or object-orientedtechniques. The software code may be stored as a series of instructions,or commands on a computer readable medium, such as a random accessmemory (RAM), a read only memory (ROM), a magnetic medium such as ahard-drive or a floppy disk, or an optical medium such as a CD-ROM. Anysuch computer readable medium may reside on or within a singlecomputational apparatus, and may be present on or within differentcomputational apparatuses within a system or network.

Different arrangements of the components depicted in the drawings ordescribed above, as well as components and steps not shown or describedare possible. Similarly, some features and sub-combinations are usefuland may be employed without reference to other features andsub-combinations. Embodiments of the invention have been described forillustrative and not restrictive purposes, and alternative embodimentswill become apparent to readers of this patent. Accordingly, the presentinvention is not limited to the embodiments described above or depictedin the drawings, and various embodiments and modifications can be madewithout departing from the scope of the claims below.

What is claimed is:
 1. A method, comprising: receiving, by a user devicefrom an intervening device, first access device identification data fora first access device; receiving, by the user device that is proximateto the first access device, a message from a second access device viathe intervening device, the message comprising message data including atleast second access device identification data, and a digital signaturethat is created by signing a hash of the at least second access deviceidentification data with a private key of a public/private key pairassociated with the second access device; obtaining the hash from thedigital signature using a public key; generating an additional hash ofthe message data; comparing, by the user device, the hash to theadditional hash; determining, by the user device, if the hash matchesthe additional hash; when the hash does not match the additional hash,automatically terminating, by the user device, any further interactionwith the second access device; and when the hash matches the additionalhash: determining that a user of the user device has not confirmed anintent to interact with the second access device; and terminating anyfurther interaction with the second access device based at least in parton determining that the user has not confirmed an intent to interactwith the second access device.
 2. The method of claim 1, wherein theintervening device is a first intervening device and wherein the messageis transmitted from the second access device to the user device via thefirst intervening device and a second intervening device.
 3. The methodof claim 1, wherein the message data further comprises an interactionvalue, and wherein the digital signature is created by signing the hashof the message data.
 4. The method of claim 1, wherein the first accessdevice and the second access device are automated fuel dispensers. 5.The method of claim 1, wherein the public key is received with the firstaccess device identification data.
 6. The method of claim 1, wherein thepublic key is associated with the second access device, and wherein themessage data further comprises the public key.
 7. The method of claim 1,further comprising: presenting, by the user device, the first accessdevice identification data in a request to interact with the firstaccess device to the user of the user device; and receiving, by the userdevice, a confirmation from the user that the user wants to interactwith the first access device.
 8. The method of claim 1, furthercomprising, when the hash matches the additional hash: presenting, bythe user device to the user of the user device, the second access deviceidentification data in a subsequent request to interact with the secondaccess device; and receiving, by the user device, an additionalconfirmation that the user of the user device wants to interact with thesecond access device.
 9. The method of claim 8, further comprising: inresponse to receiving the additional confirmation that the user of theuser device wants to interact with the second access device,transmitting, by the user device to the second access device, a secondmessage comprising second message data including the at least secondaccess device identification data and the public key, whereintransmitting the second message causes the second access device toterminate any further processing of the second message.
 10. The methodof claim 9, wherein the second access device is caused to terminatefurther processing of the second message based at least in part ondetermining that the second message data does not match the message datasent from the second access device to the user device.
 11. A userdevice, comprising: a processor; and a computer readable medium, thecomputer readable medium comprising code, executable by the processor,for implementing a method comprising: receiving, from an interveningdevice, first access device identification data for a first accessdevice; receiving, as the user device is proximate to the first accessdevice, a message from a second access device via the interveningdevice, the message comprising message data including at least secondaccess device identification data, and a digital signature that iscreated by signing a hash of the at least second access deviceidentification data with a private key of a public/private key pairassociated with the second access device; obtaining the hash from thedigital signature using a public key; generating an additional hash ofthe message data; comparing the hash to the additional hash; determiningif the hash matches the additional hash; when the hash does not matchthe additional hash, automatically terminating any further interactionwith the second access device; and when the hash matches the additionalhash: determining that a user of the user device has not confirmed anintent to interact with the second access device; and terminating anyfurther interaction with the second access device based at least in parton determining that the user has not confirmed an intent to interactwith the second access device.
 12. The user device of claim 11, whereinthe intervening device is a first intervening device and wherein themessage is transmitted from the second access device to the user devicevia the first intervening device and a second intervening device. 13.The user device of claim 11, wherein the message data further comprisesan interaction value, and wherein the digital signature is created bysigning the hash of the message data.
 14. The user device of claim 11,wherein the first access device and the second access device areautomated fuel dispensers.
 15. The user device of claim 11, wherein thepublic key is received with the first access device identification data.16. The user device of claim 11, wherein the public key is associatedwith the second access device, and wherein the message data furthercomprises the public key.
 17. The user device of claim 11, wherein themethod further comprises: presenting the first access deviceidentification data in a request to interact with the first accessdevice to the user of the user device; and receiving a confirmation fromthe user that the user wants to interact with the first access device.18. The user device of claim 11, wherein the method further comprises,when the hash matches the additional hash: presenting, to the user ofthe user device, the second access device identification data in asubsequent request to interact with the second access device; andreceiving an additional confirmation that the user of the user devicewants to interact with the second access device.
 19. The user device ofclaim 18, wherein the method further comprises: in response to receivingthe additional confirmation that the user of the user device wants tointeract with the second access device, transmitting, by the user deviceto the second access device, a second message comprising second messagedata including the at least second access device identification data andthe public key, wherein transmitting the second message causes thesecond access device to terminate any further processing of the secondmessage.
 20. The user device of claim 19, wherein the second accessdevice is caused to terminate further processing of the second messagebased at least in part on determining that the second message data doesnot match the message data sent from the second access device to theuser device.